The big problem with the LinkedIn API is that the ToS are pretty harrowing.<p>Who knows what they'll do to you if you succeed in using their (extremely valuable) data set: <a href="http://www.readwriteweb.com/archives/linkedin_platform_pros_and_cons.php" rel="nofollow">http://www.readwriteweb.com/archives/linkedin_platform_pros_...</a>
The fact that it <i>wasn't always so open</i> (especially to the developer masses) has probably steered a lot of people away from being interested. <a href="http://www.readwriteweb.com/archives/linkedin_hits_50_million_users_still_a_roach_motel.php" rel="nofollow">http://www.readwriteweb.com/archives/linkedin_hits_50_millio...</a>
There's some interesting things being done by 7 degrees, not with the LinkedIn API, but in the same space. They have pulled in so much data that you can practically find out how you're connected to anybody. They incorporate LinkedIn in the sense that you have the option to give it your LinkedIn credentials and it then scrapes your connections through it. I know exactly how I'm connected to Bill Gates, for example (i.e. I know so-and-so, who knows so-and-so, etc., who knows Bill Gates). <a href="https://www.mypeoplemaps.com/" rel="nofollow">https://www.mypeoplemaps.com/</a>